It depends on how you look at it. A diesel engine will give you much, much more torque than a petrol engine with equivalent operating costs. Whether it's worth getting a diesel depends on whether you need that torque, but I personally love having it on steep windy roads despite the fact that I never tow anything.

@TeaLeaf I did extensive research for brand new diesel car of all sizes and also taken into account the cost of servicing etc. In order for you to benefit the diesel you have to drive a minimum of 15000km/year. Anything less, is not worth it.

AA and few other websites also have similar conclusion but I think their cut off is at 16,000km.

If you're getting 2nd hand diesel make sure you check the prior servicing history. If you have a dud diesel it will give you more headache than lemon petrol.

Service history is a massive factor you should bear in mind with diesels. If it's second-hand make sure a full service history is available so you can see how well it's been looked after. When diesels go wrong, they're extremely expensive to fix.

@TeaLeaf I did extensive research for brand new diesel car of all sizes and also taken into account the cost of servicing etc. In order for you to benefit the diesel you have to drive a minimum of 15000km/year. Anything less, is not worth it.

The problem with this is how do you judge what particular petrol engine is equivalent to a particular diesel engine? Compare the two with the same power and petrol is probably slightly cheaper to run, but compare two engines with the same torque and you'll find that the operating costs of the diesel are considerably lower.

The best comparison I can think of is my Mazda3 SP22 Limited (diesel) versus the SP25 Limited (petrol). I do 8,000km per year and in theory both would work out to have the same operating costs, but the diesel has similar power and a significant advantage in torque. That makes the diesel a more efficient engine in my view.

I've had my VW Golf 2.0T Diesel for close on 5 years now and I get ~15km/L and do around 15,000KM per year. I've also got an Audi A3 2.0T Petrol (basically a Golf GTI) and that does ~10km/L and similar distance per year. Last time I worked it out fuel & RUC was costing 0.14c vs 0.18c per KM. I service both every 10,000KM, so there's no benefit to the petrol there, however the resale on the petrols appears to be slightly better so I think it's pretty much even after a few years of ownership.

Newer petrol engines are a lot more economical than they used to be, so I'd be swaying towards a petrol if I was buying a ~2013 or newer.

I looked at this and got the lower trim spec SP25 petrol. $9k cheaper than the diesel limited, and limited doesn't get you that many extra features.

alasta:

The best comparison I can think of is my Mazda3 SP22 Limited (diesel) versus the SP25 Limited (petrol). I do 8,000km per year and in theory both would work out to have the same operating costs, but the diesel has similar power and a significant advantage in torque. That makes the diesel a more efficient engine in my view.